1. Field of the Invention
This invention relates to copiers/printers, and more particularly, to an improved method and apparatus for easing the clearance of jammed sheets in copiers/printers.
2. Description of the Prior Art
In copier/printer machines, paper jams have long been a burden to users. When a paper jam occurs, the user is required to take some action to restore the system to working order and to recover the integrity of the particular job. Heretofore, various strategies and features have been developed to reduce the occurrence of jams and to minimize the burden on the user to recover from the jam. Some of these strategies include: early detection of fault conditions; controlled cycle down and cycle up of machines; purging "bad" sheets which may be damaged or out of sequence to a destination where they are easily recognized and separated from "good" sheets; and minimizing the number of steps and the number of sheets and the difficulty of removing paper from the jammed machine.
Typically, sheets downstream from the jam are delivered as good, and sheets upstream from the jam must be removed by an operator along with the jammed sheets (or they are purged on cycle up). Purged sheets must then be recognized by the user as "bad" and discarded or recycled. Dedicating an output destination as a "purge tray" facilitates the recognition of purged sheets, but such a dedicated tray may be viewed as costly and wasteful. Distinguishing purged sheets by offsetting them from other sheets in an output tray can be wasteful if there are other sheets in the compiler for stapling (which must be sacrificed for job integrity).
Thus, there is still a clear need for an improved jam clearance system.
Various prior art structures are known for detecting and remedying jam situations including U.S. Pat. No. 3,588,472, which discloses a system wherein the number of recorded sheets entering a transport path of a reproduction apparatus are monitored along with the number of copies regressing from the transport path. These respective numbers are compared with the number of copies desired, and this comparison is utilized to provide a net count in a counter to indicate the number of originals from which the requisite number of copies have been made, completed, and delivered to a sorting area. In U.S. Pat. No. 3,819,266, a copying system incorporates means to stop the system in the event of a jam. A control is provided to inhibit restarting of the system except for recycling of the document handler until the malfunction is corrected. A method is disclosed in U.S. Pat. No. 3,944,794, of programming a reproduction machine to compensate for copies lost or destroyed as a result of a paper jam during a copy run.
Included by reference herein is U.S. Pat. No. 4,078,787, which discloses a paper jam technique in a copier that causes a complete shutdown of the machine. Copier jam recovery is accomplished by opening the machine access covers, removing the jammed sheets, and closing he covers. In U.S. Pat. No. 4,231,567, a method and apparatus for clearing jams in the transport path of a copier includes the steps of sensing a jam, clustering in-process sheets either at the jam location or at an area upstream of the jam location while simultaneously allowing sheets downstream of the jam location to continue out into a catch tray and removing the jammed sheets after the last downstream sheet has exited the copier and the machine has stopped.